Liquid heating apparatus



R. A. EKSTROM, JR

LIQUID HEATING APPARATUS 5 Sheets-Sheet 1 Filed Dec. 23, 1941 @w -1 g EH T11 llxl'! 6 r w. it mw P l PM}! w -W\m\\ WM w l I w W N. Q wr /Mfi EW y 1945- R. A. EKSTROM, JR 2,375,840

LIQUID HEATING APPARATUS Filed Dec. 23, 1941 I 5 Sheets-Sheet 2 my 5' 279i y 1945- R. A. EKSTROM, JR I ,375,840

I LIQUID HEATING APPARATUS Filed Dec. 23, 1941 5 Sheets-Sheet 4 a 1945-R. A. EKSTROM, JR 2,375,340

LIQUID HEATING APPARATUS Filed Dec. 23, 1941 5 Sheets-Sheet 5 j #1 LA1770a 7230 71' Patented May 15, 1945 LIQUID HEATING APPARATUS Regner A.Ekstrom, Jr., Markham, 11]., assignor to Elematic Corporation, Chicago,Ill.,

ration oi Illinois Application December 23, 1941, Serial No. 424,120

Claims.

This invention relates to an apparatus for heating liquids by means of agas burner in which the burner or portions thereof are submerged orextend into the liquid and some or all of the products of combustionarepreferably discharged into the liquid causing agitation of the same.

The principal objects of the invention are to provide an improved burneror apparatus of the character indicated which will be particularlysimple in construction and durable and efiicient in operation.

Other objects are to provide improved means for controlling the input ofthe gases to the burner; to improve the combustion characteristics ofthe burner and to distribute and control the output or exhaust of thegases of combustion; to provide improved means for mixing the gases andpreventing danger from back-firing; to provide an improved pilot lightand ignition therefor; to provide means for continuous indication of theefiiciency of the flame or combustion; to provide means for visuallyobserving the combustion or flames in the burner; to provide means fordispensing the heated or exhaust gases throughout the area of the liquidwhereby the gases will be discharged at temperatures close to that ofthe surrounding liquid; to provide an exhaust pipe or conduit with finsto dissipate the heating; to provide an improved flame sleeve enclosingthe fiame which becomes heated sufficiently to maintain combustion afterthe burner has been started; to provide means for automaticallycontrolling the temperature of the liquid; to provide means forincreasing the temperature of the liquid without undue agitationthereof; to provide means for automatically shutting off the supply ofgases to the burner if the flame becomes extinguished; to provide animproved spark ignition electrode and means to observe the operation ofthe spark and the flame produced adjacent thereto; to provide a neonindicator which will give continuous indication of the presence of theelectric spark in the igniter and whereby the operator will know thatthe combustible mixture will be fired upon admission; to provide aburner which may be readily lifted out of the tank or liquid as forchanging or repairs; to provide certain protective features; and toprovide such other advantages and improvements as will be described morefully hereinafter.

While my improved apparatus may be used for various purposes and forheating various liquids, one of the particular uses for which it isintended is the heating of liquids used [for pickling metals such as thesulphuric acid solution used for pickling steel, and the descriptionwill be directed mainly to the burners installed for such uses.

In the accompanying drawings illustrating this invention, I

Fig. 1 is a plan view of a tank such as used for pickling steel with myimproved apparatus positione therein;

Fig. 2 is a vertical sectional view taken substantially on the line 22of Fig, 1;

Fig. 3 is an'enlarged vertical sectional view of a portion of the tankand burner taken substantially on the line -33 of Fig. 4;

Fig, 4 is an elevational sectional view taken from the right hand sideof Fig. 3;

Fig, 5 is an enlarged sectional view taken substantially on the line 55of Fig. 3;

Fig. 6 is a sectional detail of a gas mixing and protective device;

Fig. 7 is a plan view of a tank with a modified form of the burnermounted therein;

Fig. 8 is a sectional view taken on the line 8-8 of Fig. '7; i

Fig. 9 is a diagrammatic view illustrating the .burner and certaincontrol, indicating, and protecting features; and

Fig. 10 is a detail showing a modified form of gas feeding means.

The tank l5 shown in the drawings represents a pickling tank but mayindicate any suitable container for holding liquid to be heated. Theburner indicated generally by the numeral I6 is of the Venturi type,although I prefer to use gas under substantial pressure instead of thezero or low pressure commonly used in such burners. The burner has abody portion I! with an enlarged combustion chamber l8. The body portionhas a flange l9 which is engaged by a closure disc 20 secured thereto inany suitable manner. The venturi 2| is carried by the disc or plate 20and projects into the cylindrical part of the body portion I! as shownin Fig. 3. The inner end of the Venturi has a burner sleeve 22 securedor aflixed thereto. This sleeve is preferably made of cast stainlesssteel and is of conical form with its larger end terminating in thecombustion chamber. This sleeve is intended to attain a red heat whenthe burner is in operation which is suflicient to maintain combustion,and it also tends to properly form the flame.

The Venturi 2| is engaged by a T or coupling head 23 having a branch orinlet 24 for the air inlet pipe 25. This pipe is controlled by the valve26 and is also preferably provided with a transverse disc or closure-21having a reduced orifice II. The purpose of the orifice is to preventany undue back pressure in the supply pipe which might cause injury tothe air pump or other parts.

The outer end of the coupling head It has a plug or closure 29 whichcarries the gas jet or nozzle It that projects into the venturi asshown. 1

Gas is supplied to the jet by a supply pipe 3| having a controllingvalve 82. This supply pipe may be introduced under any desiredpressures.

The combustion chamber l3 has an inlet opening 34 in the wall of a bulgeor projection 35 which is preferably slightly above the inner end of thesleeve 22. One end of a pilot tube 36 engages with the inlet 34 as shownin Fig. 5. The outer end of this tube has a head 31 with a conical ortapered tubular portion or extension 38 that projects into the tube 33as shown and terminates adjacent to the inlet 34. The outer end of thetubular portion is closed by a disc 39 preferably formed of glass ortransparent material and held in position by an expansion ring 40. Theouter end of the head 31 is also closed by a disc 4| preferably formedof glass or transparent material, held in position by a ring 42. Thedisc 33 carries an electrode or terminal 43 which is supplied with hightensioned electricity through the supply wire 44 receiving current fromany suitable source.

The ignition sparks are formed between the irmer or exposed end of theelectrode and the adiacent walls of the extension 33 as indicated at 45.

Air is supplied through a. pipe 46 to a mixing chamber 41 where it ismixed with gas supplied through a pipe 48. These pipes are preferablyprovided with the reduced orifice devices 49 and 50 respectively forprotecting the main lines and apparatus connected therewith. The mixedgases pass from the chamber 41 through a pipe which connects with thetube 36 at a point just below the head 31 as shown in Fig. 5. It will benoted that the space 52 between the tube 33 and the conical extension 38gradually increases so that the gas mixture is progressively expandedtoward the end of the extension where it is ignited by the electricspark which is preferably maintained in constant operation while theburner is in use. The burning gases pass into the combustion chamber i8and ignite the mixture in the main burner which is supplied with air andgas as above described. After the main burner is in operation for ashort time, the sleeve 22 becomes red hot and will maintain combustionin the main burner even if the electrode ceasedto function. The glassdiscs 33 and 4| provide windows so that the operation of the ignitionand pilot light may be readily seen. A branch pipe 53 leads from the airpipe 48 to the cone or extension 33 slightly below the disc 39 andprovides a stream of air which is introduced to the inside of the coneto keep the insulating glass disc dry and free from moisture.

I also provide means for indicating or measuring the intensity of thegas flame in the burner. For this purpose, a tube 54 i mounted adjacentto the tube 36 with its inner end connected with the bulge or projection35 as shown in Fig. 5.

The other end of the tube is closed by means of a head II which issecured therein in any suitable manner. head II and held against ashoulder therein by means of an expansion ring 51. The end of the headII is closed by means of another glass or transparent disc 83 which isheld in position by a ring II. The disc 63 serves as an insulatingsupport for a pair of thermocouple wires 80 and 3| which preferablyextend into the projection 3! for a short distance beyond the end or thetube as shown. The thermocouple wires are connected in the usual mannerby means of wires 32 and 83 to an instrument 34 (Fig. 9) of the typecommonly used for pyrometers but which is preferably calibrated toindicate the burner efilciency. The thermocouple wires preferably do notextend into the main flame of the burner but are adapted to measure theconfined heat in and around the burner. This heat is directlyproportional to the amount of gas and air being properly burned. Theinstrument 64 serves as a B. t. u." indicator and shows when the flameis hottest for any given setting of the air and gas and-.in this ,way isa true indicator of burner efilciency. The sight opening provided by thediscs 68 and 58 permits visual inspection of the flame in the mainburner whereby the operator may readily see the actual conditions ofcombustion.

As a further means for readily indicating the spark or ignitionoperation, I provide a neon tube 65 (Fig. 9) which may be mounted on aninstrument panel and is preferably of spiral form. One end of this tubeis connected to the high tension terminal or circuit by means of a wire36 while the opposite end is not connected.

, Whenthe ignition is operating, the gas in the neon tube is therebyexcited, causing a progressive undulating light around the spiral whichis readily visible to the operator from a considerable distance. If thecurrent is flowing and the electrode does not spark, the neon spiralwill glow uniformly. If the spark electrode circuit fails or isshort-circuited, the neon spiral will fail to glow or be illuminated.The use of a neon tube for indicating the condition of an ignitionsystem provides a particularly desirable feature and is entirely novel.

The gas inlet pipe 3| may also be provided with an additional safetydevice comprising an automatic valve 61 which will close automaticallyupon failure of the gas pressure and which can only be opened manuallyas by means of a lever 33, such automatic valves being of well knownconstruction.

The combustion chamber or body of the burner connects with a pipe orburner housing extension 69' which in turn is connected by means of anelbow 10 with a horizontal discharge pipe H. The discharge pipe issupported adjacent to the bottom of the tank as shown in Fig. 2 and maybe provided with holes for discharging the heated gases or gases ofcombustion directly into the liquid to be heated as shown at 12. Whenthe burner is to be used for pickling tanks for pickling steel, in whichthe liquid is dilute sulphuric acid, I have found that such directdischarge into the liquid is apt to be objectionable as causing. oogreat agitation for ebullition and that it is preferable to distributethe discharge more uniformly throughout the bottom of the tank. For thispurpose, I provide branch pipes or ducts 13 which lead from the maindischarge pipe ll outwardly or to the sides of the tank. These pipes areclosed at their outer ends by caps or plugs 14 A glass disc I4 ismounted in the and are provided with large number of small dischargeholes I whereby a small quantity of gas will be discharged from eachopening and the gas will be uniformly distributed throughout the area ofthe tank. This will tend to permit cooling of the gases or transfer theheat to the liquid so that the gases will be at substantially the sametemperature as the liquid when they escape to the atmosphere.

The outer end of the pipe H is connected with a riser pipe 16 whichextends to the top of the tank and is provided with a valve 11 forcontrolling the exhaust from the pipe to the atmosphere. This exhaustpipe and valve serves to control the agitation in the tank as by openingthe valve, the pressure in the outlet ducts will be reduced and byclosing the valve, the pressure will be increased, thereby increasingthe volume of the gas which escapes into the liquid. This control outletalso serves to regulate the B. t. u. output of the burner and serves toexhaust the products of combustion over and above the amount requiredfor agitation and permits the combustion of larger quantities of gas andair to raise the temperature of the liquid. It is important to know thatin an apparatus of this type, the temperature ceiling is limited by theagitation for the reason that as a hotter flame is produced, theproducts of combustion are increased and if allowed to discharge throughthe liquid causing excess agitation, the increased amount of evaporationabsorbs the heat gain, thus limiting the attainable heat to about 150 F.regardless of the amount of combustion. By means of my atmosphereexhaust, air and gas can be burned to the full capacity of the burnerand the main portion of the products of combustion exhausted directlyinto the air using only a small portion for agitating the liquid. Inthis way, the temperature can be raised to approximately the boilingpoint or any desired degree and the amount of agitation easilycontrolled. Undue agitation caused by excess exhaust in pickling tanksis also haze ardous as the liquid is apt to be thrown out with apossible causing of acid burns to the workmen. My cooling and dispersingducts permit control of the size of the bubbles rising from thedistribution pipes, keeping them small in size and in intimate contactwith the solution, thereby transferring the greatest amount of heatpossible to the solution.

It will be particularly noted that a large portion of the burner and thepipesof the exhaust system are subjected to intense heat and also to theaction of the dilute sulphuric acid when the burner is used in apickling tank and the acid will flow back into the system when theganese, silicon, carbon or iron. These alloying elements are adjusted orvaried as desired, and

in some cases, aluminum bronze may also be used.

When the burner is to be operated, the valve 26 will be opened and airwill be forced into the system, thereby driving the liquid out of theburner and parts connected therewith. Current will be supplied to theignition electrode preparatory to introducing the combustible mixture tothe pilot. When such mixture is admitted through the pipe 5|, it will beignited and the name will extend down into the combustion chamber l8.Thereupon the main gas supply will be admitted through the pipe 3| andcombustion will occur in the burner to the products being exhaustedthrough the exhaust system above described. When the pilot light andburner are in operation, the combustion may be observed through thesight openings provided by the tubes 36 and 54 and the neon tube willalso indicate the condition of the spark so that the entire operation iswell under the observation and control oi. the operator. This isparticularly important in view of the comparatively large amount of gasused and the consequent possibility of danger in the event of failure ofoperation.

In the pickling of steel, it has been found that the proper agitation ofthe pickling liquid will greatly expedite the pickling operation. Theaction is also particularly efiective when the liquid is heated ,to thedesired temperature which may be effectively and economically done withmy imconnected with a burner head 19 having an air inlet pipe 80. Theburner head is closed at its upper end by a plug or closure 8| whichcarries the nozzle 32 that projects down into the venturi in the usualmanner. A pipe 83 extends upwardly from the plug 8| as-shown in Fig. 6and passes, through the chamber 84 which is supplied with gas through aninlet pipe 85. The

gas passes from the chamber 84 into the pipe 83 through a series of jets86, the ends of which are beveled or tapered as shown. The amount of gasentering the pipe may be regulated by means of an adjustable sleeve 81which fits closely over the pipe 83 and extends outwardly through agland or packing 88 and has aflange 89 at the upper end thereof. Air athigh pressure is supplied to the pipe 83 and as it passes inwardly overthe tapered ends of the jets 86, will entrain the desired amount of gasfor proper combustion which amount may be regulated by opening orclosing more or less of the jets by means of the sleeve 81. Theauxiliary or additional air supply through the pipe is in excess of theair required for combustion and its purpose is to keep the burner ductsclear when the combustible mixture of air and gas is shut off. In actualpractice, the secondary stream supplies some of the air for combustionand will dilute the mixture if it is too rich. This will effect moreperfect and dependable ignition and combustion. The beveled ends of thejets which extend into the high pressure air stream, provide a lowpressure on the lower or feed side, so that the gas will be drawn in andbe thoroughly mixed with the air. These small ports also prevent oreliminate back pressure which might cause explosive concussions to carryback to the gas pressure regulator and compressor. Such back pressurewould be apt to cause damage to This figure shows a motor driven bloweror compressor 80 which supplies air to the supply pipe 28. This pipe isprovided with a control device 8| commonly known as a pressurestat whichwill open the circuit in the main supply line if the air pressure fallsbelow a predetermined point. This device has a lever 82 for manuallyclosing the circuit,

The air supply pipe 08 which leads to the mixing T 41 has a shut oilvalve 88 which is operated by a solenoid 80. The gas pipe 48 is providedwith a shut-off valve 85 which is actuated by a solenoid 88.

The gas intake valve 82 and the air intake valve 20' are operativelyconnected with a motor 81 which is adapted to simultaneously open andclose the valves, such motor operated valves being in common use.

Current is supplied for all of the electro-responsive devices from mainsupply wires 80 and 88. Branch wires'I00, IOI lead from the main wiresto a switch I02 which is adapted to Open and close the circuit through,the wires I03 and Ill to the motor of the blower or turbine 80. A switchI08 is positioned beyond the motor switch and controls the main circuit.The wire 88 leads directly to the pressurestat 8| and the circuit iscontinued from the pressurestat through wire I08. Wires I01 and I08 leadfrom the wires 88 and I80 respectively to the solenoid 84. Branch wiresI08 and H lead to the solenoid 86 as shown. Branch wires III and II2lead to the transformer H3 which supplies current for the ignitionelectrode. The wires 88 and I00 lead to a thermostatic controlledinstrument I I4 which is of common or well known construction and whichserves to control the operation of the motor 81. Three wires H5, H6 andIll lead from the thermostatic instrument II to' the motor. A bulb H8 isinserted in the liquid in the tank and operates the thermostat through asuitable connection II8. This arrangement is such that when thetemperature in the bulb reaches a predetermined amount, the thermostatinstrument will close the circuit to the motor 81 which causes the sameto close the valves 26 and 82, thus cutting off the supply to the mainburner. When the temperature of the bulb falls to a predetermineddegree, another circuit to the motor is closed, causing the motor toagain operate and open the valves, thus again supplying gases to themain burner. The solenoids 80 and 86 will hold their respective valvesopen when current is supplied, but in the event of failure of current,these valves will automatically close, thus providing a desirable safetyfeature for the pilot.

The apparatus shown in Figs. 7 and 8 is substantially the same as thatjust described, but in this form of the invention, the entire burner I20is positioned horizontally on the bottom of the tank and the air supplypipe I2I and gas pipe I22 lead up to the top of the tank where they areprovided with couplings I28 and I24 so that they may be readilydisconnected. The burner is connected directly with the discharge oroutlet pipe I20 as shown. The outer end of this pipe or conduit isconnected with a riser pipe I26 having a control valve I21 and alsohaving a coupling I28 so that it may be readily disconnected. In theevent that any repairs or replacements are needed, the couplings to theseveral pipes may be disconnected and the entire burner and partsconnected therewith may be raised out of the tank by means of ropes orcables I28 fastened to the pipes III and I2.

The steam which is formed when water is heated in tanks such as used forvarious commercial purposes often becomes highly objectionable. In theoperation of pickling tanks or other tanks for cleaning or treatingmetals, the steam or vapor is often particularly objectionable anddestructive as it may contain some of the acid or alkali used in thebath. While my improved apparatus will prevent excessive discharge ofsteam or vapor, there will, of course, always be some formed when theliquid is heated to operating temperatures. I have discovered that suchsteam or vapor may be reduced or dissipated by subjecting the same to ablast or current of dehydrated air or hot gases such as the gases ofcombustion. When ablast of such gases is directed against the vaporrising from the evaporation, the vapor is dissipated. This apparently iscaused by the greater absorptive quality of the heated and dried gases,but in any event the dissipation of such vapor is highly desirable. Inutilizing this principle in the present apparatus. I provide the pipeI26 with branches or extensions I30 which will be around the top of thetank and are provided with holes I 8| directed inwardly over the liquid.Any moisture or vapor arising from the liquid may be subjected to thedehydrated air and gases of combustion being discharged through the pipeI26 and will be dissipated as by absorption, or the like.

The discharge pipe I25 is shown in Figs. 7 and 8 as being provided withradiation fins or discs I82 which may be cast integrally therewith ormay be applied thereto in any well known manner. These fins or suchadditional radiation or heat transfer devices are intended particularlyfor use in heating cleaning baths, or the like, containing variouschemicals or cleaning composi-- tions. The fins tend to quicklydissipate the heat from the pipe or conduit and keep its temperatureclose to that of the surrounding liquid thereby preventing chemicaldisassociation of the constituents dissolved in the liquid.

I claim:

1. In an apparatus of the character set forth, the combination of acombustion chamber,.a pipe for conducting the gases of combustion belowthe surface of a liquid to be heated, means for discharging some of thegases of combustion from said pipe into the liquid, an outlet pipeextending from the first named pipe above the surface of the liquid, avalve for said outlet pipe and means for directing the discharge gasesfrom the outlet pipe over the surface of the liquid for dissipatingvapor caused by the heating of the liquid.

2. In an apparatus for heating liquids, the combination of a burnerhaving a combustion chamber, a pilot tube leading from the combustionchamber to a point above the level of the liquid which is being heated,an electric spark igniter for lighting fuel in the pilot tube andkeeping it lighted, and means for indicating the operation of the spark,comprising a neon tube and a wire connecting one end of the tube withthe igniter circuit whereby the gas in the tube will be caused toproduce a light when the igniter is in operation.

3. A burner of the character set forth, particularly adapted for heatinglarge quantities of liquids including a body portion having a combustionchamber and closed at one end, a venturi secured to the closed end andprojecting inwardly into the body portion and having a sleeve portionextending into the combustion chamber, said sleeve portion being adaptedto become sufflciently heated when the burner is in operation, tomaintain combustion, means for supplying air to the venturi, a gasnozzle projecting into the venturi, means for supplying gas to saidnozzle which is mixed with the air in the venturi, electric ignitionmeans for igniting the gas and air in the combustion chamber and adischarge conduit leading from the chamber beneath the liquid to beheated, the arrangement being such that after the burner has beenlighted, the projecting sleeve portion will become sufficiently hot tomaintain combustion without the use of the electric ignition means.

4. A submerged burner for heating and agitating liquids comprising incombination a combustion chamber, a conduit leading from the combustionchamber for a substantial distance along below the surface of the liquidto be heated, outlet orifices spaced apart along the conduit fordischarging gases of combustion into the liquid over said surface todispel the vapor caused by I the heating of the liquid.

5. The combination with a burner having a combustion chamber, of meansfor supplying fuel and air to said chamber, a pilot tube opening intosaid chamber, means for supplying air and fuel to said pilot tube tomaintain a pilot light, an electric spark igniter coacting with thepilot tube for igniting the fuel in said tube and keeping the pilotlighted, means for supplying electric current to the igniter, and a gastube having one end connected with the circuit to the igniter andserving to indicate the operation of the igniter.

REGNER A. EKSTROM, JR.

